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Feedback loops in data

When a model’s outputs change the world (or the logs), and those changes become tomorrow’s training data—**feedback loops**.

What it is

When a model’s outputs change the world (or the logs), and those changes become tomorrow’s training data—feedback loops.

Why it matters

Ranking, moderation, fraud, and policing-adjacent tools can entrench errors if loops aren’t monitored.

How it works (plain)

Prediction → action → new data → retraining. If only some outcomes are observed (selection bias), the loop distorts harder.

Everyday example

A recommender shows fewer niche creators → they get less data → the model “learns” niches don’t exist.

Try it

Sketch a loop for one product decision. Mark what you *don’t* observe.

Myths

⚠️ Myth: Retraining weekly always improves quality.
✓ Reality: It can amplify a bad loop faster.
⚠️ Myth: Offline accuracy catches loops.
✓ Reality: You need online monitors and counterfactual thinking (Course 16).

Sources